Syntes: Lachner et al. (2025) — explaining a lesson to an imagined peer helped right away but not eight weeks later

Källa: Lachner, A., Russ, H., Hübner, N., Sibley, L. & Scheiter, K. (2025). When Does Learning by Non-interactive Teaching Work? A Large-Scale Analysis of Learner Characteristics in a Classroom Setting. Educational Psychology Review 37, 88. https://doi.org/10.1007/s10648-025-10060-0

Verified content

• [full text] Three analogous randomised classroom experiments (project GRAIL), 1,074 German grade 7–8 physics students in 11 schools (mean age 12.6), analysed together in a preregistered one-stage individual-participant analysis (AsPredicted 26p4-7vsh).
• [full text] All students had the same lesson on the converging lens (15-minute introduction, 30 minutes of experiments) from one certified physics teacher. They were then randomly assigned to 15 minutes of non-interactive teaching (recording a voice message to a fictitious peer, Mia, who had stated two common misconceptions; materials allowed but not to be read aloud) or 15 minutes of restudying the materials and taking notes. Assignment came after the lesson, so the teaching group had not studied expecting to teach.
• [full text] Scientific knowledge (ROC-CI test, 15 multiple-choice items, α = .72): immediately after, teaching beat restudy (β = 0.23, p < .001); eight weeks later the difference was not significant (β = 0.09, p = .110).
• [full text] Interest in physics moderated the eight-week effect (β = −0.18, p = .043): low- and medium-interest students did better after teaching, high-interest students did not; explained by more invested mental effort.
• [full text] Teaching raised enjoyment (β = 0.30) and mental effort (β = 0.28) and made students less overconfident about their knowledge.
• [full text] Sub-studies: Study 1 (Russ et al. 2025a) found no long-term effect; Study 3 (Russ et al., under review) found no effect of teaching immediately or after the delay.

Limits

• [full text] One short (15-minute), single, open-book session on one physics topic; the authors attribute the missing delayed effect to the short dose and low retrieval demands and leave open whether repeated or closed-book teaching would last.
• [assessment] No equivalence test: the eight-week estimate points the same way as an advantage and is not shown to be zero.

Role for C15

• [assessment] Narrowed C15 on 2026-10-25 (weakened): a lasting gain is not established for a short explanation added after ordinary study; the claim now covers learners who studied expecting to teach. Kill withheld (C15's kill-condition concerns teaching after preparing to teach).

Added 2026-10-25 by the project (nightly attack run). [full text] = read in the full text; [assessment] = the project's own assessment.